The purpose of this study is to examine the mediating role of ethical climates (ECs) on HRM practices and organizational performance (OP), specifically in educational sector administration in Nigeria. Scanty of literature attempted to discover mechanism through which HRM practices affect OP, however, still there are needs for more empirical studies to clear the assumptions in the literature. This study proposed ethical climates (ECs) as potential mediator on the relationship between HRM practices and OP. A survey method was carried out, and data were collected from some selected educational ministries, parastatals, board and agencies in Nigeria. A total of 216 questionnaires were administered, of which 181 returned and usable for the data using PLS SEM 2.0v. Based on the findings, HRM practices were found positively related to organisational performance. The study also argued that ethical climates mediate the hypothesized relationship between HRM practices and OP. The study also suggested for future research. Keywords: HRM practices, Ethical climates, Organisational performance, Educational sector.